MS Systems: Joints and Muscles Flashcards
What are the three types of joints?
+ Fibrous
+ Cartilaginous
+ Synovial
What are the features of fibrous joints?
No movement
What are examples of fibrous joints?
The suture joints of the skill and teeth
What are the features of cartilaginous joints?
+ Very strong
+ No movement
Where are primary cartilaginous joints (synchondrosis) found?
+ Costal cartilage and ribs
+ Epiphyseal plates in growing bones
Where are secondary cartilaginous joints (symphyses) found?
+ Joints of the sternum
+ Intervertebral discs
+ Pubic symphysis
What are features of synovial joints
- Fibrous capsule
- Articular cartilage
- Synovial membrane
- Intra-articular disc
- Bursae
- Synovial sheaths
What are the features of a fibrous capsule?
+ Consist of collagen fibres
+ May be thickened along lines of stress to form ligaments
+ Ligaments restrict movement, protecting the joint from damage (very commonly damaged e.g sprained ankle)
+ Intrinsic ligaments are part of the capsule
What are features of articular cartilage?
+ Hyaline cartilage
+ Creates frictionless surface
+ Poor blood supply
What are features of synovial membranes?
+ Collagenous tissue that lines the fibrous capsule
+ Secretees synovial fluid
What are features of synovial fluid?
+ Consists of hyaluronic acid, lubricin, small no. of phagocytic cells
+ Reduces friction between the articular surfaces:
- alignment of glycoprotein molecules changes with exercise
- exercise decreases viscosity so that lubrication improves (thixotropic)
+ Provides nutrients (and O2) for articular cartilage, removes waste
What are features of intra-articular discs?
+ Meniscus
+ Made of fibro-cartilage
+ Discs found in joints where there are rotatory movements
What are features of bursae?
+ Closed sacs with synovial membrane, lubricated with fluid
+ Found where friction occurs e.g between skin & bone, tendons & bone
What are features of synovial sheaths?
+ Specialised bursae that surround tendons where they are subject to pressure e.g those found in the hand and foot
What are factors that influence joint stability?
+ Shape of bones
+ Strength and position of ligaments
+ Tone of surrounding muscles
What is osteoarthritis?
Degenerative disease:
- articular cartilage
- weight bearing joints
What is rheumatoid arthritis?
Autoimmune disease:
- changes in synovium lead to destruction of articular cartilage
What is the purpose of deep fascia?
It divides the limbs into compartments (e.g in the arm - anterior/posterior
Compartments contain groups of muscles that share a function
What is superficial fascia?
Thin layer of loose fatty connective tissue underlying the dermis and binding it to the parts beneath
What is deep fascia?
Layer of dense connective tissue which can surround individual muscles
Surround groups of muscles to separate into fascial compartments
What are the components of a muscle functional group?
+ Prime mover
+ Synergists
What are features of muscle fibres?
+ Arranged in bundles or fasiculi
Divided into 3 layers:
- epimysium (dense sheath on surface)
- perimysium (lies between fasiculi)
- endomysium (separates the muscle fibres)
What is the role of myosatellite cells?
They give rise to myoblasts, which mature into myocytes
What is antagonistic muscle action?
When a group of muscles oppose the movement of another group - called the antagonists
As one muscle relaxes, the other contract and vice versa
Which type of cartilage never ossifies and where is it found?
Elastic cartilage:
- ears
- tip of nose
- epiglottis
What are features of fibrocartilage?
Forms the tough shock-absorbing discs between the symphyses in the midline of the body (intervertebral discs)
What are features of hyaline cartilage?
+ Forms the laryngeal cartilages, tracheal rings, bronchi and costal cartilages
+ May ossify later in life
+ Cushions the joint (articular) surfaces of bones in synovial joints
+ Hyaline cartilage forms the temporary skeleton of the developing foetus (cartilage model) - gradually replaced almost entirely by bone (ossification)
What are ligaments, and what are their function?
Short band of tough, flexible fibrous connective tissue:
- connects two bones or cartilages or holds together a joint.
- a membranous fold that supports an organ and keeps it in position.
What are tendons, and what are their function?
A flexible but inelastic cord of strong fibrous collagen tissue attaching a muscle to a bone
